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Carbon Nanotube Resin Shores Up Boats and Bikes

Spinoff is NASA’s annual publication featuring successfully commercialized NASA technology. This commercialization has contributed to the development of products and services in the fields of health and medicine, consumer goods, transportation, public safety, computer technology, and environmental resources.

At 100 times the strength of steel, and just one-sixth the weight, it is easy to see why engineers are excited by the potential of carbon nanotubes. But the nanoscale material is challenging to work with. NASA funding was instrumental in early research needed to put it to good use.

Special composite materials, reinforced with a carbon-nanotube-infused epoxy, make for very light, extremely tough race cars that are better able to withstand the forces of a crash.

Carbon nanotubes, made from flat carbon sheets that roll up on themselves into a tube, were first discovered by a Japanese scientist in 1991. But creating a composite of carbon nanotubes was difficult.

“If you take raw carbon nanotubes and try to put them into a composite, they just all clump up together,” said Lance Criscuolo, president of Zyvex Technologies (Columbus, OH). “Think of it as a poorly made cake batter. You’ve got lumps of stuff in there.”

Many researchers were working on how to make a useful material out of carbon nanotubes, and NASA put out a call for proposals. The agency was looking for different ideas of how to use carbon nanotubes through the SBIR (Small Business Innovation Research) program. One proposal came from Zyvex Technologies.

NASA funded four SBIR contracts with Zyvex between 2003 and 2006. The first two centered on how to incorporate carbon nanotubes into a functional material, and the later ones on using that material in a composite as a lightweight radiation shield.

Zyvex researchers devised a polymer that transformed the properties of carbon nanotubes so they would disperse in a resin, which could then be used to reinforce woven carbon-fiber materials. Working with NASA, they achieved high concentrations of carbon nano-tubes with excellent dispersion in resins, including epoxy.

“Funding from NASA was really key and important in getting us to develop the technology so that we could functionalize carbon nanotubes and get good properties with the host matrix,” said John Randall, president of Zyvex Labs, a spinoff of Zyvex Technologies.

One of Zyvex’s customers is using the material for ship landing decks designed to allow smaller boats to drive onto them — sometimes with propellers still spinning. The composite is tough enough that it doesn’t get torn up, and doesn’t add extra weight.

Often, there’s a tradeoff between toughness and stiffness — things that are very strong tend to be brittle, like glass, while things that are resilient aren’t stiff, like rubber. Carbon nanotube-infused resin helps make already strong carbonfiber composites significantly tougher without compromising the stiffness, often actually increasing the stiffness. Adding carbon nanotubes to the resin also helps the material withstand surface abrasion, so surfaces don’t wear away as quickly, and it helps divert energy into the fibers, which are stronger than the resin.

Almost immediately after the SBIR contracts, Zyvex found customers among makers of sporting goods such as baseball bats and bicycles who were excited by the combination of tougher, stronger, and lighter. Since then, the company has increased its product line dramatically. It now offers six different formulations of its carbon-nanotube additive (under the ZNT product name) that is added to different resins by the customer. The company also offers its own line of composites (under the Arovex product name) in which carbon fiber, glass fiber, and other materials are pre-treated with a carbon-nanotube-infused epoxy.

While some industries, including aerospace and marine customers, have been slower to adopt the new materials, they too are coming on board. One of Zyvex’s latest customers is using the material for ship landing decks designed to allow smaller boats to drive onto them. The landing areas need to be tough because the smaller boats would still have propellers spinning when they arrived, tearing up the deck of the other boat. Rather than making the composite at the bottom of the boat thicker and heavier, the customer uses the Zyvex material, which provides toughness without adding weight.

Zyvex is using the same technology developed under the NASA program to incorporate carbon nanotubes into rubber and other flexible materials for applications such as tires, seals, gaskets, and o-rings. The same technology is being migrated into thermoplastics for medical devices. For instance, Zyvex has partnered with a medical device company on a National Institutes of Health grant to develop a balloon catheter for insertion into arteries to help clear blockages.

Articles: Test & Measurement

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